U.S. Pat. No. 4,299,012 discloses a hose clamp which consists of an open band with overlapping band ends and which is adapted to be transferred from a closed condition in which the outer band end is connected to the inner band portion, to a tightened condition having a reduced inner dimension, comprising a tongue formed at the inner band end, an aperture provided in the outer band portion for receiving the tongue in the tightened condition, and a step which projects inwardly as seen from the outer band end, which extends transversely to the band longitudinal direction within the area of the end of the aperture nearer to the outer band end, and which has a height corresponding to the thickness of the band material. This hose clamp has proved suitable for fixing even thin, hard hoses to pipe nipples due to the fact that, in the tightened condition, the inner surface of the clamp is free of gaps and steps and therefore supports the hose at all circumferential positions.
For tightening the known hose clamp, a so-called “Oetiker ear” provided in the outer band section is narrowed by means of a pair of grippers. A tongue provided at the inner band end serves to bridge the gap remaining underneath the ear, the tongue cooperating with a tongue channel provided in the outer band portion. The channel is formed by two parallel cuts extending in the longitudinal direction of the band, wherein the two band portions outside these cuts are offset inwardly at their ends close to the outer band end, and the central portion situated between the cuts is offset inwardly at its end remote from the outer band end, each offset corresponding to the thickness of the band material.
In the closed but not yet tightened condition of the hose clamp, hooks provided at the inner band end are inserted in openings near the outer band end. The tongue and the tongue channel are so arranged and dimensioned in the circumferential direction of the hose clamp in such a way that, in this closed condition, the free end of the tongue just reaches the channel and the portion of full band width adjacent the tongue bridges the spacing between the legs of the ear.
In tightening, the tongue moves completely into the tongue channel until its end comes to lie close to the offset of the centre band portion between the two cuts, and the portion of full band width adjacent the tongue comes to lie close to the offset at the other end of the tongue channel. In this tightened condition, while gaps occur near the offsets, these gaps at no location extend across the full band width so that the hose is supported even in these regions by at least part of the band width, and tightness between the hose and the nipple is ensured over the entire circumference.
In the hose clamp known from EP 0 570 742 A1, the tongue during tightening enters a space between two beads formed in the inner surface of the outer band section, which beads project inwardly by an amount corresponding to the thickness of the band material and terminate in a step of the same height. In order to make sure that the tongue is laterally guided throughout the tightening process, the tongue and beads have such a length in the circumferential direction of the hose clamp that the tongue reaches the space between the beads already in the closed condition of the hose clamp.
U.S. Pat. No. 4,315,348 describes a hose clamp having a separate insert portion bridging the ear, with two tongue-type ends extending through windows provided in the outer band section.
The invention is based on the object to remove at least in part such disadvantages as occur with comparable hose clamps of the prior art. A more specific object may be seen in providing a hose clamp which requires an as small as possible length of band material at a given clamp diameter.
The solution of this object in accordance with the invention which consists of an open band with overlapping band ends and which is adapted to be transferred from a closed condition in which the outer band end is connected to the inner band portion, to a tightened condition having a reduced inner dimension, comprising a tongue formed at the inner band end, an aperture provided in the outer band portion for receiving the tongue in the tightened condition, and a step which projects inwardly as seen from the outer band end, which extends transversely to the band longitudinal direction within the area of the end of the aperture nearer to the outer band end, and which has a height corresponding to the thickness of the band material, that the length of the tongue is substantially shorter than the difference between the inner dimension of the hose clamp in its closed condition and that of the hose clamp in its tightened condition, and that the outer band portion in the region between its outer band end and the aperture has means for laterally guiding the tongue prior to its entry into the aperture. The tongue provided at the inner band end is guided during tightening of the hose clamp consecutively by two different measures wherein, during the first part of the tightening movement, the tongue is remote from the aperture and only in the second portion enters the aperture and is guided by it. The tongue can thus be shorter by roughly one half than in the prior art, which results in a corresponding saving in band material length.
The embodiment wherein the aperture is a window for the tongue to pass in the tightened condition of the hose clamp leads to a specifically safe guiding and retaining of the central band section transverse to the band.
An easily obtained possibility of guiding the tongue in the first part of the tightening movement is obtainable wherein the guiding means includes beads formed in the outer band portion on both sides of the tongue clamp of claim 3 and wherein the inner band end portion has two beads in the area adjacent the tongue in the band longitudinal direction, which beads are engaged, in the tightened condition of the hose clamp, by the two beads in the outer band portion and wherein the width of each bead is ¼ to 1/10 of the band width.
For reducing the friction which occurs between the tongue and the outer band portion during tightening of the hose clamp a point-shaped embossment facing the outer band portion is provided near the free end of the tongue.
A specifically safe guidance of the tongue transverse to the band longitudinal direction in the first part of the tightening movement is provided when the guiding means includes a slot continuous with the aperture in the outer band portion and a projection on the outer side of the tongue for engaging the slot and wherein the projection is a nose punched out of the tongue.
The invention is adapted for use with hose clamps with and without ear-like tightening means wherein an ear-type tightening means is provided between the guiding means and the outer band end and wherein an undulation is provided between the guiding means and the outer band end.
Advantageous embodiments will now be explained in more detail with reference to the drawings. In the drawings,